1. Technical Field
The present invention relates to a camera module and a method of fabricating the same.
2. Description of the Related Art
In recent years, portable phones including digital cameras are becoming widely popular. A camera module used for most portable phones includes an optical lens and an image sensor that converts incident light passing through the optical lens into an electrical signal. The electrical signal converted by the image sensor is transmitted to an image signal processing unit (ISP) and output as an image signal.
More specifically, incident light passes through the optical lens, a micro-lens and an RGB filter and is incident on a photodiode. The photodiode generates charges corresponding to the intensity of the incident light, converts the charges into an electrical signal, and transmits the electrical signal to the ISP. In this case, the image sensor is electrically connected to a substrate, which is connected to an external image processor, using bonding wires or metal bumps.
The camera module includes, in general, an image sensor chip, a substrate on which the image sensor chip is disposed, a barrel disposed on the substrate, and a lens and a near infrared (NIR) filter inserted into the barrel. According to the conventional art, since the foregoing components are fabricated separately, it is difficult to miniaturize the components. This technical restriction leads to the increase of the fabrication costs. Furthermore, the image sensor chip is typically assembled while being exposed to atmosphere, thus causing a drop in yield due to particle contamination from the atmosphere.
In order to overcome the foregoing drawbacks, it has been recently proposed that a lens structure could be formed on a transparent wafer using polymers that can be hardened by exposure to ultraviolet (UV) light. The resultant lens structure could be bonded to a substrate having an image sensor chip using spacers formed of low-temperature polymers or metallic materials, and divided into respective camera modules using a dicing process. In this method, the lens structure can be easily fabricated. However, even if the bonding process is performed at a low temperature, polymers may be deformed at the process temperature, thus resulting in the deformation of the lens structure. Since the deformation of the lens structure may bring about the deformation of an image, it is necessary to develop a new technique that can reduce the thermal budget of the bonding process.
Furthermore, the dicing process includes mechanically cutting the spacers. However, due to the spacers having a high hardness property, technical problems, such as chipping and cracks, may be caused during the mechanical cutting process. The present invention addresses these and other disadvantages of the conventional art.